When an electronic equipment stop running, it is often the result of a problem that involves excess current flow that destroys components and may also damage the printed circuit board to which they are attached. The conductive traces on a circuit board are thin copper pathways that can easily melt under excessive current conditions. Fortunately, it is possible to repair broken or melted traces when they occur.

Determine the cause of the damage and replace the faulty component(s). If the root problem is not addressed, the board will be damaged in a new place, or worse yet, additional components could fail.

Using the edge of the razor knife, scrape away any black carbon deposits and any melted material that formed when the trace burned open. The board should be clean and free of debris where you intend on splicing the damaged trace. The ends of the traces on either side of the gap formed by the damage should be scraped to expose one to two millimeters of clean, shiny copper.

Using the soldering iron, heat the cleaned traces on either side of the gap and apply some fresh solder to make a clean shiny coating on the ends of the traces.

Using the bare wire, prepare an appropriately shaped wire splice to fit between the ends of the traces to fill the gap between them. Make sure the wire overlaps the exposed ends of the traces. The wider the original trace, the more strands of wire should be used to approximate the same cross sectional area as the original trace. You can be liberal about how you do this since it is not critical, but use common sense and make the repair look esthetically pleasing. A typical approach is to use a single piece of wire and zig-zag back and forth a few times between the ends of the traces.
 
Solder the wire in place by heating each side of the repair in turn, applying solder to attach the wire to the ends of the two traces.